CPU factors: dynamic factors for CPU

[simgrid.git] / examples / cpp / exec-cpu-factors / s4u-exec-cpu-factors.cpp

diff --git a/examples/cpp/exec-cpu-factors/s4u-exec-cpu-factors.cpp b/examples/cpp/exec-cpu-factors/s4u-exec-cpu-factors.cpp
new file mode 100644 (file)
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+++ b/examples/cpp/exec-cpu-factors/s4u-exec-cpu-factors.cpp
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+/* Copyright (c) 2010-2021. The SimGrid Team. All rights reserved.          */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/* This example shows how to simulate variability for CPUs, using multiplicative factors
+ */
+
+#include <simgrid/s4u.hpp>
+
+namespace sg4 = simgrid::s4u;
+
+XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_test, "Messages specific for this s4u example");
+
+/*************************************************************************************************/
+static void runner()
+{
+  double computation_amount = sg4::this_actor::get_host()->get_speed();
+
+  XBT_INFO("Executing 1 tasks of %g flops, should take 1 second.", computation_amount);
+  sg4::this_actor::execute(computation_amount);
+  XBT_INFO("Executing 1 tasks of %g flops, it would take .001s without factor. It'll take .002s",
+           computation_amount / 10);
+  sg4::this_actor::execute(computation_amount / 1000);
+
+  XBT_INFO("Finished executing. Goodbye now!");
+}
+/*************************************************************************************************/
+/** @brief Variability for CPU */
+static double cpu_variability(const sg4::Host* host, double flops)
+{
+  /* creates variability for tasks smaller than 1% of CPU power.
+   * unrealistic, for learning purposes */
+  double factor = 1.0;
+  double speed  = host->get_speed();
+  if (flops < speed / 100) {
+    factor = 0.5;
+  }
+  XBT_INFO("Host %s, task with %lf flops, new factor %lf", host->get_cname(), flops, factor);
+  return factor;
+}
+
+/** @brief Create a simple 1-host platform */
+static void load_platform()
+{
+  auto* zone        = sg4::create_empty_zone("Zone1");
+  auto* runner_host = zone->create_host("runner", 1e6);
+  runner_host->set_factor_cb(std::bind(&cpu_variability, runner_host, std::placeholders::_1))->seal();
+  zone->seal();
+
+  /* create actor runner */
+  sg4::Actor::create("runner", runner_host, runner);
+}
+
+/*************************************************************************************************/
+int main(int argc, char* argv[])
+{
+  sg4::Engine e(&argc, argv);
+
+  /* create platform */
+  load_platform();
+
+  /* runs the simulation */
+  e.run();
+
+  return 0;
+}